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Cells. Chapter 3 Bio 156 Fall 2006. What is the Cell Theory?. All organisms are made of cells. The cell is the smallest unit of life. New cells come from pre-existing cells. What are microscopes? tools used to view cells.

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Chapter 3

Bio 156

Fall 2006

What is the Cell Theory?

  • All organisms are made of cells.

  • The cell is the smallest unit of life.

  • New cells come from pre-existing cells.

What are microscopes?tools used to view cells

  • Compound light microscope: light rays focused by lenses, viewed by the eye, magnifies up to 1000X

Dissecting microscope:

  • For observing surface details of objects, magnifies up to 30X


Electron microscopes

  • For viewing details, magnifies 1,000,000X


Surface of a cell, cilia

How are cells classified?according to their internal organization?

  • What structures do all cells have?

  • Cell or plasma membranes: living phospholipid bilayer and associated proteins

Internal organization of cells cont…..

  • Plant cells also have a rigid cell wall made of cellulose

  • Cytoplasm: a semifluid gel inside the cell that contain cell contents

What are Eukaryotic Cells?Have a “true nucleus”, plant and animal cells

  • What are organelles?"little organ", cellular structures that perform specific functions

  • What does the nucleus do?control center of the cell

What are prokaryotic cells? “before" the nucleus (bacteria)

Bacillus polymyxa

DNA: single circular DNA in a nuceloid region

  • Ribosomes: enzymes that synthesize proteins

  • Cell membrane: regulates transport in/out of the cell

  • Cell wall for strength, may have a capsule or slime layer

How does cell structure reflect cell function?

  • Simple cuboidal epithelium (400x) is made up of one layer of cube-shaped cells.  These cells frequently make up the tubes of your body.

How does cell structure reflect cell function…..

  • Blood Cells

  • Why do you think Red Blood Cells don’t have a nucleus and White Blood Cells do?

  • (hint: think about their functions)

How does cell structure reflect cell function…

  • Skeletal muscle (400x) is striated

  • What is the function of these cells?

  • Why do you think these are long cells?


How does cell structure reflectcell function…

  • Plant Cell Anacharis (Elodea) leaf cells (1000x). 

  • What do you think is the function of these cells? 

  • How is the function dependent on the structure?

How does cell structure reflect cell function…

Potato cells with stained leucoplasts (100x). 

  • The leucoplasts (starch storage units) have been stained with gram iodine (stains for starch)

What limits cell size?

Surface area-to-volume ratio needs to be greater for an exchange of materials

Microvilli: some cells increase surface area by micro-extensions called microvilli


What is a plasma membrane made of? (how is a cell membrane like a house?)

  • Phospholipids:a. polar heads (hydrophilic or water soluble) b. nonpolar tails (hydrophobic or not water soluble)

  • Cholesterol: gives strength to the cell membrane

  • Proteins: transport, communication

What is the fluid-mosaic model of the cell membrane?

  • How is itfluid? (flows, pliable) phospholipid bilayer

  • How is it a mosaic? proteins partially or wholly embedded

What are channel proteins? Space where a substance moves across the membrane

What are carrier proteins?

Combine with a substance and

help it move across the membrane


What are receptors? Specific shape that allows a molecule to bind to it, ex) hormone

What are glycoproteins?For cell to cell identification


How are membranes selectively permeable?Allows some molecules to pass through and not others

  • What is passive transport?

  • Doesn't need energy to happen, goes with concentration gradient

  • What is diffusion? Movement of molecules from high to low concentration


What is osmosis? Diffusion of water into and out of cells

  • What is a solute? usually a solid

  • What is a solvent? usually a liquid

  • Define tonicity: based on concentrations of solutes

What are isotonic solutions?

Same concentration of solutes on either side of the membrane


What are hypotonic solutions?

  • Low solutes in solution, water enters the cell, hemolysis


What are hypertonic solutions?

  • High solutes in solution, causes water to leave the cell (water follows salt), crenation


What is turgor pressure? Plant cells swell in response to a hypotonic solution

Put some wilted celery in a glass of cool water. If it has not wilted too much, it will become stiff again. This is because of turgor pressure when the plant cell vacuoles become filled with water, push against the cell walls and become firm.

What is facilitated transport?Carrier proteins assist movement of specific molecules

What isactive transport?Requires ATP to move molecules against their concentration gradient

  • What is the Na-K pump?

    • Concentrates more Na+ outside, K+ inside cell membranes


What is Exocytosis or Endocytosis? Move materials outside or inside the cell


What is Phagocytosis?“Cell eating”, white blood cells


What isPinocytosis?“Cell drinking”, root cells get water


What is receptor-mediated endocytosis? Coated proteins attract specific molecules to the cell surface


Construction of the Cell Membrane

  • This is an interactive activity

  • Construction of the Cell Membrane

  • In this activity you will learn about the cell membrane structure by assembling it. Interactive exercise from Wisc-Online.


How do internal structures carry out specific functions?

  • What are the structures of the nucleus?

    • Nuclear membrane: has nuclear pore spaces

    • Nucleolus: forms RNA and ribosomes

    • Chromatin: all of the DNA molecules

What do ribosomes do?Assemble proteins

What does endoplasmic reticulum (ER) do?

  • Makes and transports large molecules

  • Smooth ER: enzymes make lipids, steroids

  • Rough ER with ribosomes (RNA): have ribosomes for making protein

What does the Golgi apparatus look like? Stacks of sacules (like pancakes)

  • What is its function?

    • Stores and distributes products from ER

    • Processes, packages and secretes

    • Breaks off pieces as vesicles (small sac)

What are Vacuoles? Large membranous sacs for transport and storage

  • What do lysosomes do?

  • Digestive enzymes in vesicles

  • What are Peroxisomes?

  • Vesicles with enzymes that destroy toxins

What are mitochondria? Site for aerobic respiration, "burns food"

  • Produces ATP “cell's powerhouse”

  • Cristae: inner membrane increases surface area for metabolism

  • Matrix: inner fluid-filled space

What are chloroplasts? Organelles only found in plant cells

  • Photosynthesis: use solar energy to make carbohydrates

  • Thylakoids: interconnected flattened sacs

  • Grana: stacks of thylakoids (granny's pancakes)

  • Stroma: syrupy fluid filled space (syrup)

What provides cells with structure for support and movement?

  • Cytoskeleton? interconnected microtubules and microfilaments

    • Cilia: small whips, move cell, or fluids across a surface

    • Flagella: larger whip, moves cell like an oar on a boat

Centrioles in animal cells for spindle fibers during mitosis, pull chromosomes apart

How do cells use and transform matter and energy?

  • What are metabolic pathways? When one chemical reaction leads to another ex) A + B -> C + D

  • What are reactants? participate in a reaction, ex) A + B -> (enzyme)

  • What are products? result from a reaction, ex) C + D

What is Anabolism?

Building up of larger molecules, takes energy (endergonic)

What is Catabolism?

Breaking down into smaller molecules, gives up energy (exergonic)

What is ATP?A universal packet of energy used in cells

  • ATP = adenosine triphosphate (Adenine-ribose-P-P-P)

  • Exergonic:the energy currency of the cell

    • ATP -> ADP + P + energy

  • Endergonic:

    • ADP + P + energy -> ATP

What is cellular respiration?Chemical reactions that produce ATP in cells

  • What is glycolysis? breaks down glucose (C6) -> 2 pyruvate (C3) + 2 ATP

  • Where does it take place? in the cytoplasm, in all cells, no O2 needed

  • How does it get started? it needs 2 P from 2 ATP activate glucose

What is aerobic respiration?Respiration with oxygen

  • Where does it take place? Inside the mitochondria: yields 36-38 ATP

  • What does the Krebs cycle do?1) pyruvate is broken down to O2 + acetyl group (C2) -> 2 CO2 + 2 ATP 2) NAD+ and FAD + H2 -> NADH and FADH2 -> electron transport system

What does theelectron transport system do?

  • Coenzyme carriers move electrons to make 32-34 ATP

What is fermentation? Alternative pathway of energy when no oxygen is present

  • Glycolysis first

  • Alcoholic fermentation:

    • Glucose is broken down to pyruvate, then to Alcohol + CO2 + 2 ATP

  • Used for: brewing, baking

What is lactic acid fermentation?

  • Glucose -> pyruvate –> lactate + 2 ATP

  • Used in making yogurt,

    sour cream, cheese,


  • In O2 starved muscles,

    oxygen debt:

    O2 + lactic acid to


Need more help?

  • For extra learning practice see links on Bb under CH 3

  • Read your test clues each night before you go to bed to help remember them

  • For extra credit fill out review sheet (1 pt) and write 15 multiple choice questions and answer them (1 pt)

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